The field of the invention is that of the sensors which provide an electrical output signal corresponding to a sensed condition, and the invention relates more particularly to novel and improved sensors which are programmable in accordance with tested temperature characteristics of the sensors to compensate for change in the output signal due to a change in temperature of the sensors.
Acceleration sensors formed by silicon micromachining techniques conventionally employ a proof-mass portion of a silicon body which is resiliently supported on a frame portion of the body by integral silicon beams. Piezoresistive elements are formed in the silicon material of some of the beams and display change in resistance when the beams experience strain as the proof-mass moves relative to the frame when subjected to an acceleration force. The piezoresistive elements are connected in a bridge circuit to provide an electrical output signal corresponding to the changes in resistance due to the acceleration force. Such acceleration sensors have attractive properties relative to size and cost and also have other desirable performance characteristics. However, the piezoresistive elements which contribute substantially to achieve the cost and performance advantages of the sensors are quite temperature sensitive so that there is substantial change in offset and gain in the output signal with change in sensor temperature.